The article I have chosen to summarize is called Role of a New Mammalian Gene Family in the Biosynthesis of Very Long Chain Fatty Acids and Sphingolipids. This article focuses on fatty acids and their uses and who and what they are found in. According to the article many biological processes depend on fatty acids containing 20 or more carbon atoms. These are known as VLCFA or very long chain fatty acids and are found in the brain, skin, testis, and some glands. A fair amount of VLCFA is amide-linked to a long chain sphingoid base sphinganine forming a ceramide which supports the lipid backbone. Distribution bias for VLCFA is controlled by substrate specificity of the matching fatty acyltransferases. The article states that sphingolipids are essential for cell proliferation, stating that impaired sphingolipid synthesis leads to cessation of the cell growth in yeast and mammalian cells. The unique structural properties of sphingolipids will strongly contribute to epidermal water barrier and also help electric insulation of myelin. The sphingolipids in the plasma membranes bulkiness permits the sugar groups of glycosphingolipids to act in cell recognition and adhesion. In the article it states there has been mass evidence that implies sphingolipids and their degradation products in signal transduction and formation of functional lipid microdomains in the plasma membrane. It was found suppressor mutations in sphingolipid deficient yeast mutants have shown that glycerophospholipids holding VLCFA can mime sphingolipid structures. This allows yeast growth in the absence of sphingolipid. The elongation process involves 4 steps: condensation, reduction, dehydration, and a second reduction. The article implied that to this day there is little known about the genetic nature of mammalian fatty acid chain elongation enzymes. The study was done on male mice kept at 28C for 1 week, some were then exposed to 4C, the mice were killed by cervical dislocation and tissues were dissected and directly subjected to RNA extraction. Cerebral Ssc1 and mRna  levels in dysmyelinating mutants heterozygous were obtained. They then cloned the mice cDNA. The scientists compared the Cig30 cDNA sequence to the EST data base and they found a lot of highly similar nucleotide sequences. The study found all mouse EST cDNA fragments seemingly conformed to two novel mRNA species.  A clone of each cluster was acquired because of the I.M.A.G.E consortium. After careful analysis of the clones to total RNA taken from several mice in the experiment, the study found that both genes were expressed in the liver. The polypeptides are really similar in size and in sequence. Amino acid sequence of SSC1, SSC2, and CIG30 with homologous yeast polypeptides show that sequence identity in the different mice yeast protein pair is ~30% and they each contain 100% conserved motifs characteristics of the protein family.

Citations

Petr, T. et al. Role of a New Mammalian Gene Family in the Biosynthesis of Very Long Chain Fatty Acids and Sphingolipids. Journal of Cell Biology 149, 707-718 (2000).